Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
  • C07C51/10—Preparation of carboxylic acids or their salts, halides or anhydrides by reaction with carbon monoxide
  • C07C51/14—Preparation of carboxylic acids or their salts, halides or anhydrides by reaction with carbon monoxide on a carbon-to-carbon unsaturated bond in organic compounds

Definitions

• the present invention relates to an improved process for the manufacture of alkylcarboxylic acids (where alkyl is of 6 to 20 carbon atoms), by hydrocarboxylating the corresponding olefins of 6 to 20 carbon atoms.
• the hydrocarboxylation of olefins, in accordance with the following equation ##STR1## R alkyl is a conventional process for the manufacture of alkylcarboxylic acids.
• the above conventional syntheses relate to the use of cobalt carbonyl compounds as catalysts, since the nickel carbonyl compounds and noble metal carbonyl compounds which are also conventionally used for carbonylations give even less advantageous results when used for the hydrocarboxylation of the higher olefins, either in respect of the yield or because of the technical difficulties resulting from the volatility of nickel carbonyl or because of losses of noble metals, eg. palladium or rhodium.
• alkylcarboxylic acids where alkyl is of 6 to 20 carbon atoms
• alkylcarboxylic acids where alkyl is of 6 to 20 carbon atoms
• hydrocarboxylating the corresponding olefins by means of cobalt carbonyl compounds in the presence of a solvent, in higher absolute yield and with a higher space-time yield if from 0.2 to 3 kg of N-methylpyrrolidone, per kg of the olefin, is used as the solvent.
• Suitable starting compounds include both unbranched and branched olefins with a terminal or non-terminal double bond. According to the conventional rules, these olefins merely differ in reactivity, which generally decreases with increasing degree of branching and with increasing steric screening of the double bond. However, the lower reactivity of such olefins can be substantially counterbalanced by using more severe reaction conditions. Linear ⁇ -olefins react particularly easily and, as a result of the presence of N-methylpyrrolidone in accordance with the invention, predominantly give the N-alkylcarboxylic acids, which in the main are the desired products.
• the process is also of particular importance for hydrocarboxylating propylene and butylene oligomers, e.g., trimeric propylene, tetrameric propylene and diisobutylene. These are frequently isomer mixtures, so that the products obtained are also mixtures of isomeric carboxylic acids.
• preferred olefins are linear olefins and mixtures of olefins of 8 to 15 carbon atoms as obtained on cracking paraffin.
• the process is carried out under the conventional reaction conditions for hydrocarboxylation, i.e., under a CO pressure of from 100 to 1,000 bars and at a temperature of from 150° to 220° C.
• a CO pressure of from 100 to 1,000 bars and at a temperature of from 150° to 220° C.
• from 1 to 2 moles of water and from 0.01 to 0.1 mole equivalent (expressed as cobalt) of the cobalt catalyst are used per mole of olefin.
• the cobalt can be employed in the form of dicobalt-octacarbonyl, but cobalt salts, e.g.
• cobalt acetate or cobalt palmitate in general fulfil the same purpose, since the active carbonyl complexes are formed in situ under the reaction conditions.
• the cobalt salts (cobalt soaps) of the carboxylic acids formed during the process are particularly suitable.
• the preferred amount of N-methylpyrrolidone is from 0.5 to 1.5 kg/kg of olefin.
• the process can be carried out batchwise but as a rule a continuous method is preferred, for economic and technological reasons.
• the procedure followed is, in general, to charge the reactor with the solution of the dicobalt-octacarbonyl in the olefin, and with aqueous N-methylpyrrolidone. If the cobalt is employed in the form of its salts, these can also be added to the aqueous solvent phase.
• air is passed through the reaction mixture, whereby the cobalt compound is reconverted to the Co-II form.
• a different oxidizing agent preferably hydrogen peroxide, can be used.
• the mixture is then subjected to fractional distillation. N-Methylpyrrolidone and unconverted olefin are recycled, as is the high-boiling residue which contains the cobalt and which, before introduction into the reactor, is advantageously dissolved in the olefin.
• the desired carboxylic acids are obtained in yields of from about 75 to 90%. From about 5 to 20% are accounted for by unconverted olefin and the remainder is in the form of by-products, including, above all, the paraffin corresponding to the olefin.
• the economics of the process taking into account the yields, by-products and process costs, are throughout from about 10 to 50% better.
• the higher alkylcarboxylic acids are in the main used for the manufacture of plasticizers, dryers and corrosion protection agents.
• the yield of 3,5,5-trimethylhexanoic acid was 78%. 15% of the olefin remained unchanged, 5% were hydrogenated to the paraffin and the remainder comprised aldehydes, esters and other by-products.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)

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Citations (9)

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• 1977
  • 1977-03-04 DE DE2709438A patent/DE2709438C3/de not_active Expired
• 1978
  • 1978-02-01 US US05/874,316 patent/US4619790A/en not_active Expired - Lifetime
  • 1978-02-23 BE BE185433A patent/BE864265A/fr not_active IP Right Cessation
  • 1978-03-01 JP JP53022175A patent/JPS6058900B2/ja not_active Expired
  • 1978-03-03 GB GB8500/78A patent/GB1595037A/en not_active Expired
  • 1978-03-03 AT AT154178A patent/AT356641B/de not_active IP Right Cessation
  • 1978-03-03 FR FR7806146A patent/FR2382425A1/fr active Granted

Patent Citations (9)

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